Lucanus cervus (Linnaeus, 1758)
European Stag Beetle
POLYPHAGA Emery, 1886
SCARABAEOIDEA Latreille, 1802
LUCANINAE Latreille, 1804
LUCANINI Latreille, 1806
Lucanus Scopoli, 1763
The Stag Beetle is the largest of the U.K. coleoptera fauna. It has a wide global distribution, occurring throughout Europe and east through Asia Minor to Japan. There are several foreign subspecies, some of which are larger in size than our U.K. specimens. In the U.K. it occurs mostly in the south-east of England and while it remains locally common there has been a decline in recent decades; because of its long life cycle it is particularly vulnerable to habitat destruction. Adults are also killed by cars on the road; it is active nocturnally and perhaps attracted to headlights. Nonetheless there are still ‘good’ areas worth surveying for the species; suitable habitats around London and the Home Counties, Suffolk, West Sussex and Oxfordshire are still strongholds. There are also populations in the Severn Valley and the coastal south west. The species is distinctive; large, up to 70mm (body length), and sexually dimorphic with the males possessing hugely developed mandibles. In the males polymorphism with respect to head and mandible development is strong, in the less developed forms the head is narrow and the mandibles are rather straight and lack the well developed internal teeth. The typical habitat in the U.K. is gardens, wooded parkland and pasture and basically anywhere with a good continuity of large trees and suitable dead wood. On the continent it is more a species of forested areas. Adults appear from late May to early August and are crepuscular and nocturnal. They fly strongly and rather noisily and this may be the first hint of their presence. They may be observed on woodland margins etc. and they are attracted to light. Where there is a good population it is not difficult to observe the males ‘wrestling’ and pairs copulating, generally on low branches or logs. Females lay eggs in decaying logs or at the base of trees, often in the roots. A range of deciduous trees are chosen but oak seems to be preferred. Larvae burrow through the wood, feeding for up to four years, only rarely for longer, before heading into the soil to pupate in an earthen chamber. Pupation occurs in late summer or autumn and this stage may last for two or three months, the fully developed adults remain in the chamber to emerge the following year. The larvae are generally found in numbers within a stump or log pile and they are distinctive; crescent-shaped, creamy and translucent with orange head and legs, and powerful mandibles. They posses comb-like structures on the legs with which they stridulate.
The adults of both sexes should be immediately obvious, only Dorcus might be mistaken for a female Lucanus but in that species the front tibiae have longitudinal striae and the upper surface is entirely black.